Australian researchers have developed a new adaptive distributed control strategy for electric vehicle (EV) integration that incorporates both microgrid and EV-side conditions for primary frequency control. They have proposed new indices to evaluate the charging and discharging characteristics of electric car batteries and the satisfaction of electric car owners.
To include V2G-ready EVs in frequency control, current approaches have focused primarily on the battery state-of-charge (SoC), which does not distinguish between EVs with varying owner expectations. However, higher satisfaction among electric vehicle owners may increase their interest in providing these ancillary services in the future.
Now, researchers from Griffith University, Queensland, Australia, and Macquarie University, New South Wales, Australia, propose a new adaptive distributed control system to regulate the proportion of electric vehicles in primary frequency control in an island microgrid, taking into account both usage limits and ownership. expectations.
Various adaptive droop parameters are developed for this purpose. Instead of using the SoC to represent the functionality of an electric vehicle to participate in frequency regulations, researchers have introduced the Charge Capability of Battery (CCoB) and Discharge Capability of Battery (DCoB) indices to evaluate these capabilities in real time.
“With these indices, it is possible to evaluate the contribution of electric cars not only by the SoC level, but also by the time that electric car owners expect to spend at charging stations. Vehicles with the same SoC but different expansion durations are treated differently. The results show that the proposed adaptive control system provides both an electric car and a microgrid side benefits,” they write in their paper.
The proposed method provides the EV owner with a higher level of SoC during frequency control, which is subject to multiple uncertainties, and thus leads to better EV owner satisfaction, the researchers find. With the help of the EV Owner Satisfaction (EOS) index, it is possible to evaluate charging methods, incentive programs and other activities that can affect the participation of electric cars in supporting the main grid.
Finally, the implementation of this strategy has been found to prevent ramp-up issues in cases where a large number of EVs with similar SoCs are ready to participate, which adversely affects the stability of the microgrid.
The findings were discussed in a recent paper in Applied Energy, “Adaptive Control of V2Gs in Islanded Microgrids with EV Owner Expectations.”